Automatic rod feed for metal removal



March 23, 1948 E. MEINCKE 2,438,344

AUTOMATIC ROD FEED FOR METAL REMOVAL Filed May 19, 1945 Confl-ol Con+roiUni? Uni? 0- 0 r 0 Q I To blowpipe NVENTOR ATTORNEY Patented Mar. 23,1948 AUTOMATIC ROD FEED FOR METAL REMOVAL Edward Meincke, Scotch Plains,N. J assignor to The Linde Air Products Company, a corporation of OhioApplication May 19, 1945, Serial No. 594,659

6 Claims. 1

This invention relates to the removal Of metal thermochemically from abody composed of metal, such as stainless steel, which ordinarily cannotbe cut or machined by the oxy-fuel gas process.

In the thermochemical method of cutting stainless steel with heat and astream of oxygen, it is known practice to feed a piece of ferrous metalinto the reaction zone by hand. However, such practice was relativelyslow and inefficient; because an insuficient quantity of ferrous metalis fed into the reaction zone, and the process was dependent upon theskill of the operator. Also, it resulted in a rough kerf, and was notapplicable to precision cutting, but was confined to demolition work.

The main object of this invention is to eliminate the human element andinsure that a sufficient quantity of ferrous metal is fed continuouslyinto the reaction zone, by the provision of a novel'method of and meansfor feeding the ferrous metal or other adjuvant material in accordancewith the need therefor; another object of the invention is to increasethe speed and elliciency of the operation by the provision of meansacting to preheat the adjuvant material prior to its introduction intothe reaction zone; other objects are to provide automatic means forcontrolling the rate at which the adjuvant material is fed into thereaction zone as a function of the use thereof, and reducing the cost ofthe process by the use of adjuvant material in the form of inexpensiveiron wire, for example.

According to the invention, in order to increase the speed of theprocess, the adjuvant material in the form of a solid member, such as aniron rod or wire, is preheated to elevate its temperature to a pointapproaching that of the ignition temperature so that the metal burnsmore rapidly when it is moved into line with the cutting oxygen streamissuing from the blowpipe nozzle. A continuous and ample supply ofburning iron is thus provided in the oxygen stream which results inraising the temperature of such stream, as well as the deposition on thesurface of the work, of molten and burning iron which raises theemperature of the stainless steel surface to the melting point at whichplace a thermochemical reaction occurs and the molten surface materialis driven ahead and thus removed by the kinetic energy of the oxygenstream.

In carrying out this process, the rate of rod feed, the rate of cuttingoxygen flow, and the speed of the desurfacing process are closelycoordinated, otherwise the stability or continuity ,wires composed ofiron or steel.

of the operation is adversely affected. According to the invention, suchvariables are properly controlled so that the process is stable. Inorder to regulate one of the variables, i. e. the rate of rod feed,according to the invention, such rate is governed by utilizing theconductivity of the ionized path of the work preheating gas flame. Thearrangement is such that the rod is fed at a slightly higher rate thanis necessary to carry out the reaction, such rate being automaticallyreduced when the rod is fed into the flame, so that the feeding of therod is automatically regulated by the electrical conductivity of theflame. Thus the rate of rod feed is controlled as a function of the roduse by virtue of the conductivity of the work preheating flame.

In the drawing:

Fig. 1 is a diagrammatic view of apparatus exemplifying the inventionfor desurfacing or deseaming metal;

Fig. 2 is a similar view of a modification for cutting metal, and

Fig. 3 is a circuit diagram of a control circuit modification of theinvention.

Referring to Fig. 1 of the drawing, a deseaming or desurfacing blowpipenozzle N is shown inclined in operative position with respect to worl: Wwhich may be a body composed of any nonferrous metal or stainless steel.In the illustrated example, the nozzle N discharges a characteristicstream 0 composed of commercially pure oxygen against the top surface ofthe work W as the latter is moved in the direction of the arrow withrespect to the nozzle N, although it will be understood the nozzle N maybe advanced with respect to the work when the latter is stationary. Thenozzle N also discharges a plurality of oxy-fuel gas flames F forpreheating the top surface of the work W for proper thermochemicalreaction with the cutting oxygen stream 0'.

The flames F are electrically conductive and this phenomenon is utilizedto regulate the feeding of members R composed of any suitable adjuvantmaterial, such as ferrous metal. The members R are preferablyinexpensive rods or The rods R are positioned with respect to theinclined nozzle N so that one is vertical and the other is inclined andpositioned under the nozzle. The vertical rod R is preheated as it isfed downwardly in the direction of the arrow by any suitable auxiliarypreheating means such, for example, as an oxyfuel gas head H which isadapted to produce a row of heating flames J which impinge on theproceeds.

rod. Preheating the adjuvant material greatly improves the efliciencyand stability of the deseaming and desurfacing operation.

The rods R are fed into the flames F by feeding devices D which aredriven by motors M. The input circuits I of the motors M are operativelyassociated with control units C which are connected to suitable sourcesof electrical supply by circuits S. The control units C are maderesponsive to the conductivity of the flames F by suitable circuitsincluding conductors l and I2 which are electrically connected to thenozzle N and the rods R; 'both the nozzle and the rods being composed ofelectrically conductive material. Brushes I4 are provided forelectrically connecting the conductors [2 to the rods R as the latterare fed toward the flames F by the motors M.

The inclined lower rod R is not provided with any auxiliary preheatingmeans H because such rod is fed into a zone of very high temperature,and at a more acute angle into the work preheating flame F of the nozzleN. However, it will be understood that the inclined lower rod may beprovided with auxiliary preheating means H if necessary or desirable.

In the operation of the system shown in Fig. 1, the rate at which therods are fed into the flames F is automatically controlled by theelectrical conductivity of such flames, the operation of the controlunits being responsive to such conductivity, and controlling the motorsM in accordance therewith. Thus, adjuvant material is supplied to thereaction zone in sufficient quantity to maintain the stability of thethermochemical deseaming or desuriacing of the surface E of the work Wasthe latter is advanced in the direction of the arrow.

Referring to Fig. 2 of the drawing, there is shown an oxy-iuel gascutting blowpipe B having a nozzle N, the blowpipe being mounted on asuitable carriage (not shown) for movement in the direction of the arrowabove the work W so as to form a kerf K therein as the cutting operationA member R of suitable adjuvant material, such as ordinary iron wire, isautomatically fed into the work preheating flame F and the cuttingoxygen stream 0 of the nozzle N by feed device D which is driven byarmature A of a shunt motor M. Priorto being fed into the preheatingflame F of the nozzle N, the member R is moved past a flame heating headI-I, so that the flames J suitably preheat the member R.

The conductivity of the flame F is adapted to control the feeding rod ofthe member R by suitable means comprising a circuit including a batteryP, conductor [0, blowpipe B, nozzle N, flame F, rod R, brush l4 andconductor l2. Such circuit also includes a resistance Z which isconnected to the input circuit of a space discharge device or tube 'I.The output circuit of the space discharge device T includes coil l6 of arelay [8, and a suitable plate supply (not shown) connected to theterminals 26. The relay 18 also includes a normally open switch 22 whichis adapted to be closed when the relay coil I6 is energized by theoperation of the space discharge device T. The armature A of the motor Mis connected to a suitable source of electrical supply by the circuit Sthrough an adjustable resistor 24, the shunt field winding SF of themotor M being connected to the supply circuit S through a variableresistor 26 in series with the field winding. With the switch 22 closedthe resistor 26 is adjusted so that the armature A drives the feeddevice D at a certain speed which is slightly higher than that necessaryto feed the rod R into the flame F and cutting oxygen stream 0. When therod R contacts the flame F, the space discharge device T is biased tocut-ofi, deenergizing the relay l8 causing the switch 22 to open placingthe resistor 24 in the armature circuit, thus decreasing the speed ofthe motor armature A and the rate at which the rod R is fed into theflame.

Referring to Fig. 3 of the drawing, there is illustrated a modifiedcontrol circuit which includes a meter type relay 28 connected incircuit relation with the blowpipe and a rod, so as to be responsive toconductivity of the work preheating flame, The output circuit of relay28 is connected to a control circuit similar to that described above inconnection with Fig. 2. The operation of the control circuit shown inFig. 3 is also substantially similar to that described above inconnection with Fig. 2, except that the relay 28 takes the place of thespace discharge device T.

It will be understood that the illustrated examples thereof may bemodified without departing from the invention, For example, theelectrical conductivity of the flame may be detected by any suitabledetector circuit including such 7 flame. The invention is very effectivein the removal or" metal from a body composed of any metal whichordinarily resists progressive oxidation by the sole action of an oxygenjet on a heated portion thereof.

I claim:

1. The combination with a blowpipe for pro ducing an electricallyconductive oXy-fuel gas flame, and -feeding means for feeding anelectrically conductive rod into said flame, of automatic control meansresponsive to electrical current flow through such oxy-fuel gas flamebetween said rod and said blowpipefor automatically regulating the rateat which said rod is fed into the flame, said automatic control meanscomprising a, relay having an input circuit responsive to changes insuch current flow and an output circuit operatively associated with saidfeeding means for regulating the rod feeding rate to maintain apredetermined current flow through such flame.

2. Metal removing apparatus comprising a blowpipe nozzle adapted todischarge a composite stream of metal-removing oxygen and electricallyconductive work-preheating oXy-fuel gas flames, feed devices adapted tofeed rods of electrically conductive adjuvant solid material into thestream of oxygen, each rod being fed through at least one of suchflames, separate electromotlve means for driving each of said feeddevices. and separate automatic means acting to control each of saidelectromotive means so that each rod is,

fed substantially in accordance with the rate of burning of such rod insuch oxygen stream, each of said automatic means including an inputcircuit comprising such rod and said nozzle and a source ofelectromotive force.

3. Metal working apparatus comprising a blowpipe nozzle adapted todischarge a composite stream of cutting oxygen and at least oneworkpreheating oxy-fuel gas flame adjacent thereto, a feed device foradvancing an electrically conductive member of adjuvant solid materialthrough such flame into the stream of oxygen, a source of electromotiveforce connected to said nozzle and rod and having a circuit through suchflame, means driving said feed device, and automatic control meansoperatively associated with said driving means and said circuit focontrolling the rate at which the conductive member is fed to maintain apredetermined current flow through such flame.

4. Metal working apparatus as defined by claim 3, in which auxiliarymeans is provided for heating the conductive member to a temperatureapproaching the ignition temperature of the adjuvant solid material,before the conductive member is fed into such flame, for the purpose ofstabilizing the metal working operation of the apparatus.

5. In combination, means for feeding an elongated electricallyconductive member of adjuvant solid material at a certain maximumpredetermined rate, a cutting blowplpe for discharging means forthermochemically consuming said member including means for producing anoxyfuel gas stream to form a work-preheating oxyfuel gas flame and forproducing a stream of cutting oxygen, and automatic means responsive tocontact of such member with said flame for decreasing the rate at whichsuch member is fed into the cutting oxygen stream, so that the member isfed at a rate commensurate with its consumption by such oxygen stream,said automatic means comprising a flame contact detector circuitincluding said blowpipe and such member in series relation with asuitable source of electromotive force and such flame.

6. The method of removing metal from a body composed of metal whichordinarily resists progressive oxidation by the sole action of an oxygenjet on a heated portion thereof, which method 6 comprises feedingrelatively to the body being treated an elongated member composed ofreadily oxidizable adjuvant metal into a work-preheating oxy-fuel gasflame and a stream of metal removing oxygen which are applied to suchbody so as to thermochemically remove metal from the body, automaticallyfeeding the member longitudinally of itself at a substantially constantrate first into such flame and then into the stream of oxygen, andheating said member to a temperature approaching its ignitiontemperature with oxygen directly before it is fed into such flame, so asto increase the stability and efficiency of the metal removal operation,

EDWARD MEINCKE.

REFERENCES CITED The following references are of record in the OTHERREFERENCES Metals Handbook, 1939 edition; published by Am. Soc. forMetals.

